Apparatus for molding articles of uneven thickness

ABSTRACT

A method of and apparatus for preforming moldable compositions of fibrous materials and a binder in which the preform had portions along its width having different thicknesses corresponding to different thicknesses of the final molded product. Initially the composition is formed into a mat which has a thickness at least equal to the thickest portion of the preform, and then excess material is removed from across the width of the mat by scalping rolls to develop the contoured preform having different thicknesses. Each section of the mat having a different thickness is weighed separately to insure proper density of that section of the mat. Following the weighing step, the mat is again shaped into the contoured preform and placed into a mold for a subsequent heating and pressing operation.

United States Patent Haas et al.

APPARATUS FOR MOLDING ARTICLES OF UNEVEN THICKNESS Inventors: Herbert G.Haas; Edmund Munk, both of Oberstenfeld; Alfred Fink, Uhingen; ErichKlink, Faurndau, all of Germany Assignee: Werzalit-Pressholzwerk J. F.Werz, Jr. KG (Oberstenfeld/Wurttemberg Germany Filed: June 30, 1969Appl. No.: 837,649

Related U.S. Application Data Continuation-in-part of Ser. No. 698,050,Jan. 15, 1968, abandoned, which is a continuation of Ser. No. 437,107,Mar. 4, 1965, abandoned.

Foreign Application Priority Data 18/26 R, 2 EM; 264/109, 112; 156/360,62, 62.2

[56] References Cited UNITED STATES PATENTS 2,737,997 3/1956 Himmelheberet a1. ..18/4 B X 2,822,024 2/1958 Himmelheber et al., ..264/109 XPrimary Examiner-Theron E. Condon Assistant ExaminerHorace M. CulverAttorney-Patrick D. Coogan, John M. Crawford and Leslie G. NollerABSTRACT A method of and apparatus for preforming moldable compositionsof fibrous materials and a binder in which the preform had portionsalong its width having different thicknesses corresponding to differentthicknesses of the final molded product. Initially the composition isformed into a mat which has a thickness at least equal to the thickestportion of the preform, and then excess material is removed from acrossthe width of the mat by scalping rolls to develop the contoured preformhaving difierent thicknesses. Each section of the mat having a differentthickness is weighed separately to insure proper density of that sectionof the mat. Following the weighing step, the mat is again shaped intothe contoured preform and placed into a mold for a subsequent heatingand pressing operation.

7 Claims, 3 Drawing Figures PATENTEUMAY 16 I972 7 3,668,137

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EDMUND MU/YK z ALFRED Fl/YK BY mm KU/YK APPARATUS FOR MOLDING ARTICLESOF UNEVEN THICKNESS CROSS-REFERENCES TO RELATED APPLICATIONS Thisapplication is a continuation in part of application Ser. No. 698,050filed Jan. 15, 1968, and now abandoned. That application was acontinuation of application Ser. No. 437,107 filed Mar. 4, 1965, and nowabandoned. The latter application claimed priority from an applicationfile No. F42245lc/39a filed Mar 7, 1964, in the Federal Republic ofGermany.

BACKGROUND OF THE INVENTION 1. Field of the Invention Field of thisinvention is the method of and apparatus for molding a contouredvarticle having different thicknesses across a cross-section through thearticle. The article is made by compression of a mixture of comminutedfibrous materials with suitable binders. The method and apparatusspecifically are for forming a preform prior to compression.

2. Description of the Prior Art There are various methods and apparatusknown in the prior art for automatically preforming these materialsprior to their compression so as to form flat layers for the purpose ofproducing flat molded articles of substantially uniform thicknesses,such as fiber board, chip board, or the like. These materials are firstmixed and then spread onto a plate to form a layer of the requiredthickness. The thickness will depend upon the rate of the subsequentcompression and the thickness of the panel to be produced. The densityof the loose material is as uniform as possible within the entire layer.For attaining the best possible products, it has also been found that itis advisable to weigh the loose material very accurately so that theweight of each batch conforms exactly to the weight of the final moldedproduct, taking, of course, into consideration the reduction in weightcaused by the evaporation of moisture during the actual moldingoperation which is usually carried out under heat and pressure. In thismanner it is possible to attain panels of a substantially uniformdensity and a uniform specific gravity.

While these methods and apparatus may be employed very successfully forautomatically producing flat molded panels, boards, and the like of ahigh quality, they can, of course, not be used for producing moldedarticles of irregular cross-sectional dimensions, especially if thesearticles are also required to have an all-over uniform density and auniform specific gravity of predetermined values, or different densitiesand different specific gravities of predetermined values at differentparts thereof.

It has therefore in the past been necessary to carry out at least someof the steps preceding the actual molding operation of articles orirregular cross-sectional dimensions by manual labor, It requires nomore than common sense to understand that, apart from the fact that thisinvolves very tedious work and increases the cost of productionconsiderably, it is practically impossible to attain such moldedproducts either with an exactly uniform density and specific gravity oreven with different particular valuesof density and specific gravity atdifferent parts thereof. Although by mere chance or careful trial itmight be possible to attain one or even a few molded articles of suchirregular cross-sectional dimensions which might comply fully with allrequirements, a mass production and especially one on an economic scalewould be impossible. One of the results of such uncontrolled densityvalues is that, if such molded products are to be subjected to specialsurface treatments, for example, by veneering them or coating them withresin-impregnated paper, an excessively high number may be deficient inappearance or become subsequently deficient, for example, by theabsorption of moisture, and may either have to be scrapped immediatelyor cause serious complaints of customers when the defects become evidentsubsequently.

SUMMARY OF THE lNVENTlON The present invention is directed to a methodof and an apparatus for forming a preform of comminuted fibrous materialand binder for a final product in which the cross-section of the producthas varying thicknesses and the entire product has a required density sothat there will be no soft spots or holes in the molded material.

One feature of the invention is the provision of a number of prefonningrolls which may have varying diameters and varying spacial relationshipswith the conveyor carrying the moldable material so that the preformingrolls will have an outer contour along their actual directionsubstantially in proportion to the irregular surface of the final moldedproduct. The rotating rolls shape or form the surface of the loosefibrous material to the shape of the surface of the final article bymilling ofi excess parts of the material.

The separate preforming rolls are all driven at the same peripheralspeed regardless of their diameter. This requires that each of the rollsbe driven independently of the others. The separate axles of the rollsmay be tilted so that the entire roll is at an angle to the conveyorpassing beneath it.

The material is carried to the preforming rolls by the conveyor formedof one or more belts. If a plurality of belts are used, each belt willhave a separate drive.

Another feature of the invention consists in employing a secured set ofpreforming roll or rolls subsequent to the original shaping rolls forthe additional purpose of compacting the layer or layers sufficiently sothat the preform may then be fed directly into a press to be molded toits final size or to form an intermediate product which is later againcompressed, preferably in a heated mold, to its final size and shape.This is especially useful if the article is of simple shape and thedifferent parts have relatively small differences in height.

Another feature of the invention consists in the provision of suitablemeans, for example, a discharge brush roll or rolls for removing theloose preformed material from the conveyor belt and feeding it into themold.

A further important feature of the invention consists in the provisionof suitable means for propelling the loose preformed material into themold so as to pack the material therein at a uniform density despite thedifference in height of different parts of the mold or, if required, atdifferent densities at different parts of the mold. These means may beeither of a pneumatic type or a mechanical type, for example, apropelling roll or several such rolls of different diameters and of ashape similar to that of the preforming roll or rolls. These will fillthe mold so that all parts thereof, despite their different height, willbe completely filled simultaneously and at the desired density ordensities of the material.

A considerable advantage of these propelling means is also attained bythe fact that by the impact of the fibrous materials in the mold, thefibers orient themselves so as to lie in substantially the samedirection and therefore the solidity of the final product as wellas itsresistance to subsequent deformation due to moisture are considerablyincreased. Without such acceleration the fibers would extend in variousdirections and the solidity of the molded products would be veryunreliable. A further advantage of these propelling means is that theyeliminated the danger that the fibrous materials, when being filled intothe mold merely by gravity and entirely unoriented so as to extend invarious directions, might form bridges and thereby cavities underneaththese bridges or at least parts in which the material does not possessthe same density as in other parts so that the different parts of thefinal molded article will also not possess either a uniform density andsolidity, or the required specific gravity.

Another very important feature of the invention consists'in weighing theloose fibrous material, preferably after it has first been treated byone or more preforming rollers in the manner as above described, so thatthe different parts of the material, after their proper volume has beendetermined so as to be in the proper proportion to the different partsof the mold, will also have the required specific gravity or gravitiesin proportion to the specific gravity or different specific gravities ofthe different parts of the molded product.

A feature of the apparatus according to the invention therefore consistsin providing suitable multiple scales, that is, a scale which consistsof a plurality of individual scales side-byside which are adapted toweigh the different amounts of the loose material independently of eachother as required for the shallower and deeper parts of the mold. Thenumber of individual scales depends upon the cross-sectional shape ofthe molded product and the accuracy of the specific gravity or gravitiesas may be required in the final product. This division of the scaleinto'a plurality of scales may be necessary especially because of thedifferences in the specific gravity of different parts of the loosefibrous material which may come from different sources. For example, inthe production of chip board, the wood chips may come from differenttypes of wood of different specific gravities or, even if they come fromonly one type of wood and even from the same tree, some parts thereofwill be heavier than others. Thus, even if the loose material ispreformed so as to have the proper volume and density, it may varyconsiderably in specific gravity which may seriously affect theproperties of the final product. These scales may also take into accountthe loss of weight of the material due to the evaporation of moisture inthe actual molding of the final product and even the different losses ofweight of the different parts of the final product due to theirdifferences in height.

Another advantage which is attained by the invention consists in thefact that, due to the preforming operation of the loose material and thenew method of filling the molds, the latter may be of a smaller and moresimple construction than was previously required when the fillingoperation was carried out manually.

Still another advantageous feature of the invention consists in theprovision of suitable means for adjusting the preforming rolls as wellas other parts of the apparatus, if necessary, so as to vary to heightof the entire preformed layer of fibrous materials as well as the heightof different parts thereof so as to attain molded products of differentthicknesses, different specific densities, and different shapes.

In the event that the article to be molded in the direction transverseto the feeding movement of the loose material, but should vary at leastto some extent in the longitudinal or feeding direction, a single scalemay suffice and several weighing operations may be carried outintermittently on the successive parts of the layer of loose fibrousmaterial. The required difference in height of the layer in itslongitudinal direction may also be attained either in place of or inaddition to such successive weighing operations by varying the distanceof the axis of the preforming roller or rollers from the associatedconveyor belt. This effect may be further controlled or increased byalso varying the speed of the conveyor belt or belts upon which theloose material is deposited. Of course, if the article to be moldedvaries in height in both directions and the fibrous material is also tobe weighed by a multiple scale in the manner as previously described,the height of the layer on the receiving belt or belts on which thematerial is deposited after being weighed may also be varied in thelongitudinal direction either by driving this belt or these belts atdifferent speeds or by varying the height of the axis of the equalizingroller or rollers from this belt or by combining these two features witheach other.

In any event when a single scale or a plurality of scales sideby-sideare employed in the method according to the invention, each of thesescales is provided with means for interrupting the further feedingmovement of loose material by the feeding belt or belts to the scale orscales when the required weight is reached. These means are preferablydesigned so as first to slow down the feeding movement of the belt orbelts when the scale or scales are nearly filled before stopping thefeeding movement entirely when the scale or scales indicate the fulldesired weight.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view withportions cut away to show the internal details of the apparatus.

FIG. 2 is a diagramatic cross-section from the side showing theapparatus in FIG. 1.

FIG. 3 is a diagramatic cross-section from the front showing theapparatus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The apparatus comprises aloading bin 10 which is filled through chute 9 with a batch of finelyshredded fibrous materials, for example, wood chips, which are mixed inthe proper proportions with a thermosetting binder, This loading bin 10is defined at one side by an inclined conveyor belt 11 or a plurality ofsuch belts side-by-side. If a plurality of belts is used, each is drivenby a separate motor or speed reduction mechanism so that the speed ofeach belt may be varied from the speed of the other belts to conveydifferent amounts of materials simultaneously to a rotating preformingroll 12 which is adopted to form the upper surface of the layer of loosematerial in proportion to the difference in height of the difi'erentparts of the article to be molded. The preforming roll 12 is formed by anumber of preforming rolls 12a, 12b, 12c, 12d and 12e having a commonaxis but different lengths and diameters in order that the outer contourof the preform roll will shape the mat into a preform of the desiredcontour. If necessary each of the individual rolls 12 may be ondifferent axis and driven separately so that the entire preform rollwill have the same peripheral speed. It is also possible to use rolls 12of the same diameter but which are spaced at different distances fromthe conveyor belt 11 in order to provide a proper contour to the mat. Ifnecessary, the axle of the roll 12 or each of the rolls 12a 122 may betilted from the horizontal. The individual preforming rolls 12 may beadjustable to different lengths or be exchangeable for others whendifferent mat contours are required.

The material milled from the upper side of the layer on the belt 1 1 bythe preforming roll or rolls 12 is thrown back by the roll into theloading bin 10.

After passing from the preforming roll or rolls 12, the loose but formedmaterial is removed from the upper end of the conveyor belt 11, forexample, by means of one or more brush rolls 13, shown as having acontour similar to the contour of preforming rolls l2, and passed into amultiple scale 14. The scale 14 has a plurality of laterally adjacentscales 14a, 14b, 14d and Me which are adopted to weigh the differentparts of the fibrous material. These different parts have been measuredvolumetrically by the preforming roll or rolls 12. The number of thescales 14 depends upon the shape of the final molded article and thedesired degree of accuracy of its weight distribution across thedirection transverse to the feeding direction. When the weight of thematerial in an individual scale approaches the desired weight, forexample, the weight of that part in the final molded article minus theweight of the moisture which will be expelled or evaporated during theactual molding operation or operations, the scale actuates suitableswitch means S, connected in circuit with the drive motor M of theconveyor belt 11, for reducing the speed of the conveyor belt 11 untilthe scale indicates the accurate desired weight. The scale againactuates the switch means so as to stop the movement of the belt 1 1 andpreferably also the prefon'ning roll 12 and the brush roll 13 which maybe driven through appropriate transmission means from the motor M sothat no further material will be added to the scales. If an individualbelt section l1al1e, preform roll l2al2e and brush roll 13a-13 is usedfor an individual scale 14a14e then each individual scale will stop itsindividual belt, preform roll and brush roll. If a single drive is usedfor the belts and rolls, then the first scale to reach desired weightwill stop the system and the other scales must be filled by hand todesired weight. The material in each scale is kept separate from thematerial falling into the adjacent scales by the plates 15 extendingbetween the brush rolls l3 and the scales 14.

After each of the scales reaches desired weight, a suitable switch 8connected in circuit with operating means 0 cooperating with the bottomof each scale will open the bottom of each scale 14, dropping weighedmaterial through a chute or plurality of adjacent chutes 16 onto one ora plurality of adjacent discharge conveyor belts 17. Within the lower,narrower end opening of the chute or chutes 16 one or more distributors18 may be mounted for properly distributing the material on thedischarge belt 17 and for preventing it from being packed thereon by theimpact. The distributors 18 may take the form of brush rolls.

Above the discharge conveyor belt or belts 17 another preforming roll 19or plurality of such rolls side-by-side are mounted which carry. out thesame function as the preforming roll or rolls 12 and are contoured anddriven in the same manner. These rolls mill off the excess parts of thematerial on the belt or belts 17 so that the layer thereafter has againthe proper shape and density in proportion to the molded product. At theend of the discharge belt or belts l7, suitable means, for example, aproperly shaped discharge brush roll 22 or a plurality of such brushrolls side-by-side are provided for removing the preformed layer fromthe belt or belts l7 and propelling them downwardly toward the mold 21.The mold 21 is moved longitudinally as shown by the arrows, underneaththe apparatus until filled and then either cold pressed to compress thematerial into an intermediate product or directly hot pressed tocompress and thermoset the material to form the final product.

The propelling action of the discharge brush roll or rolls 22 or ofadditional propelling means 20 subsequent thereto is of importance forthe purpose of filling the deeper parts of the mold 21 as quickly as'andat the same density as the material which is filled into the shallowerparts. It is, however, of still greater importance that by being thusaccelerated, the fibrous materials, for example, wood chips, will beoriented by their impact in the different parts of the mold so that allof them will thereby be deposited in the mold in a substantiallyhorizontal position. These additional propelling means may be of apneumatic or mechanical type. In FIGS. 1-3 they are illustrated in theform of a special propelling roll or rolls 20 intermediate the dischargeroll or rolls 22 and the mold 21.

For adjusting the apparatus to different kinds of molds, the variousrolls 12, l3, l9 and 22 should be adjustable to different distances fromthe respective conveyor belts, and the axis of the different rollsshould also be adjustable to different angles to the horizontal so thatone side of each roll may be adjusted so as to be spaced a greaterdistance from the respective conveyor belt than its other side.Furthermore, the apparatus may also be designed so as to produce moldedarticles with different heights in the longitudinal direction. For thispurpose suitable adjustable control means may be provided forautomatically changing the distance between the last preforming rolls,the discharge rolls, and the associated conveyor belt. For the samepurpose, it is also advisable to provide suitable means for varying thespeed of the conveyor belts.

Although our invention has been illustrated and described with referenceto the preferred embodiments thereof, we wish to have it understood thatit is in no way limited to the details of such embodiments but iscapable of numerous modifications within the scope of the impendingclaims.

Having thus fully disclosed our invention what we claim is: 1. Anapparatus for automatically preforming a mixture of comminuted materialand a binder to produce a moldable blank of substantially uniformdensitand havin in transverse directlon of the blank portions of dierent thic ness, said apparatus comprising a plurality of scale means,one for each of said portions of different thickness of said blank, saidplurality of scale means being arranged side-by-side in said transversedirection; means for feeding into each of said scale means part of saidmixture; means for stopping further feeding when the respective scalemeans has received a part of said mixture which has a weightsubstantially in proportion to the corresponding transverse portion ofthe desired blank to be produced; means cooperating with said scalemeans for discharging the weighed parts therefrom; conveyor meanspositioned below said scale means for receiving said weighed partstherefrom in said transverse direction so as to form a layer therefromand for feeding said layer in a direction substantially normal to saidtransverse direction; forming means cooperating with said conveyor meansand the layer formed thereon for shaping the upper surface of said layerto form in said layer transverse portions of substantially uniformdensity and each having a thickness in proportion to the differentthickness of the transverse blank portions to be produced; and means forremoving said layer from said conveyor means and for feeding saidtransverse portions of said layer in the same transverse arrangementinto a mold having a mold cavity whose depth varies in said transversedirection in accordance with the desired different thickness of theblank portions to be produced so as to fill said mold to a substantiallyuniform level.

2. The apparatus as defined in claim 1, wherein said forming meanscomprise a plurality of rotatable rolls, one for each portion of saidlayer, each of said rolls having a peripheral surface arranged withrespect to the upper surface of said conveyor means so that thegeneratrix which, during rotation of the respective roll is closest tosaid surface, is spaced therefrom a distance substantially equal to thethickness of the respective layer portion.

3. The apparatus as defined in claim 2, wherein said plurality of rollsare rotatable about a common axis, and wherein said rolls have differentdiameters.

4. The apparatus as defined in claim 1, and including rotary means forpropelling said transverse portions of said layer after being removedfrom said conveyor means at an increased velocity higher than the speedof said conveyor means into said mold while the latter moveshorizontally and in a direction substantially normal to said transversedirection.

5. The apparatus as defined in claim 1, wherein said means for feedingparts of said mixture into said scale means comprise additional conveyormeans having a discharge end located above said scale means; means fordepositing said mixture on said additional conveyor means to form alayer of said mixture thereon; and preforming means upstream of saiddischarge end for shaping the upper surface of the mixture layer on saidadditional conveyor means to form in said layer transverse portions ofsubstantially uniform density and each having a thickness in proportionto different thickness of the transverse blank portions to be produced.

6. The apparatus as defined in claim 5, wherein said preforming meanscomprise rotatable preforming roll means having an outer contour in saidtransverse direction and being arranged with respect to said additionalconveyor means in such a manner so as to form in said layer on saidadditional conveyor means said transverse layer portions. 7

7. The apparatus as defined in claim 6, and including drive meanscooperating with said additional conveyor means and said preforming rollmeans for rotating the latter in a direction opposite to the movement ofsaid conveyor means.

1. An apparatus for automatically preforming a mixture of comminuted material and a binder to produce a moldable blank of substantially uniform density and having in transverse direction of the blank portions of different thickness, said apparatus comprising a plurality of scale means, one for each of said portions of different thickness of said blank, said plurality of scale means being arranged side-by-side in said transverse direction; means for feeding into each of said scale means part of said mixture; means for stopping further feeding when the respective scale means has received a part of said mixture which has a weight substantially in proportion to the corresponding transverse portion of the desired blank to be produced; means cooperating with said scale means for discharging the weighed parts therefrom; conveyor means positioned below said scale means for receiving said weighed parts therefrom in said transverse direction so as to form a layer therefrom and for feeding said layer in a direction substantially normal to said transverse direction; forming means cooperating with said conveyor means and the layer formed thereon for shaping the upper surface of said layer to form in said layer transverse portions of substantially uniform density and each having a thickness in proportion to the different thickness of the transverse blank portions to be proDuced; and means for removing said layer from said conveyor means and for feeding said transverse portions of said layer in the same transverse arrangement into a mold having a mold cavity whose depth varies in said transverse direction in accordance with the desired different thickness of the blank portions to be produced so as to fill said mold to a substantially uniform level.
 2. The apparatus as defined in claim 1, wherein said forming means comprise a plurality of rotatable rolls, one for each portion of said layer, each of said rolls having a peripheral surface arranged with respect to the upper surface of said conveyor means so that the generatrix which, during rotation of the respective roll is closest to said surface, is spaced therefrom a distance substantially equal to the thickness of the respective layer portion.
 3. The apparatus as defined in claim 2, wherein said plurality of rolls are rotatable about a common axis, and wherein said rolls have different diameters.
 4. The apparatus as defined in claim 1, and including rotary means for propelling said transverse portions of said layer after being removed from said conveyor means at an increased velocity higher than the speed of said conveyor means into said mold while the latter moves horizontally and in a direction substantially normal to said transverse direction.
 5. The apparatus as defined in claim 1, wherein said means for feeding parts of said mixture into said scale means comprise additional conveyor means having a discharge end located above said scale means; means for depositing said mixture on said additional conveyor means to form a layer of said mixture thereon; and preforming means upstream of said discharge end for shaping the upper surface of the mixture layer on said additional conveyor means to form in said layer transverse portions of substantially uniform density and each having a thickness in proportion to different thickness of the transverse blank portions to be produced.
 6. The apparatus as defined in claim 5, wherein said preforming means comprise rotatable preforming roll means having an outer contour in said transverse direction and being arranged with respect to said additional conveyor means in such a manner so as to form in said layer on said additional conveyor means said transverse layer portions.
 7. The apparatus as defined in claim 6, and including drive means cooperating with said additional conveyor means and said preforming roll means for rotating the latter in a direction opposite to the movement of said conveyor means. 